Nepeta is a genus of about 250 species of flowering plants in the family Lamiaceae. The members of this group are known as catnip or catmint because of their famed effect on cats. The scent of Nepeta pleasantly stimulates cats’ pheromonic receptors. Oil isolated from catnip by steam distillation is a repellent against insects, in particular mosquitoes, cockroaches and termites. Research suggests that in a test tube, distilled nepetalactone, the active ingredient in catnip, repels mosquitoes ten times more effectively than DEET, the active ingredient in most insect repellents but that it is not as effective as a repellent on skin.

Nepeta cataria (Catnip, True Catnip, Catmint or Field Balm) is a 50 to 100 cm tall herb resembling mint in appearance, with greyish-green leaves; the flowers are white, finely spotted with purple. Catnip is mainly known for the behavioural effects it has on cats, particularly domestic cats. When cats sense the bruised leaves or stems of catnip, they may roll over it, paw at it, chew it, lick it, leap about and purr, often salivating copiously. Some cats will also growl and meow. This reaction only lasts for a few minutes before the cat loses interest. It takes up to two hours for the cat to “reset” after which it can come back to the catnip and have the same response as before. Young kittens and older cats are less likely to react to catnip. Approximately two thirds of cats are susceptible to the behavioural effects of catnip. The phenomenon is hereditary; for example, most cats in Australia are not susceptible to catnip, since Australian cats are drawn from a relatively closed genetic pool. It elicits such a response in only some cats and it is such a dramatic response because a genetic element is involved that is enriched in domesticated breeds. There is some disagreement about the susceptibility of lions and tigers to catnip. Some claim that both lions and tigers are affected by catnip, while others say that only lions are affected. In a recent television documentary released by Animal Planet called Stalking the Jaguar, scientists used a form of catnip to attract a jaguar to a camera point for filming. Upon attraction, the jaguar reacted in the exact same way that domestic cats react to catnip, suggesting further proof of the genetic existence of the susceptibility to catnip outside of domestic felines.